1. Introduction
This invention relates to the treatment of hydrogels to reduce or eliminate their irritant effect when used for physiological applications, such as for soft contact lenses and to the materials treated by the methods of this invention.
2. Description of the Prior Art
Certain polymers and copolymers and hydrogels thereof are known to have physiochemical properties which make them suitable for prolonged contact with living tissue, blood and mucous membranes such as would be required for surgical implants, blood dialysis devices and the like. Hydrogels are known which are useful for the formation of so-called "soft" contact lenses such as, for example, as described in U.S. Pat. No. 4,056,496 incorporated herein by reference.
Before a hydrogel article, such as a soft contact lens or other biological article, is placed in contact with living tissue, it is generally prepared by known methods which include treatment with organic solvent and with aqueous solutions such as saline solutions. Typically, the hydrogel article is treated by boiling in a solvent, such as alcohol; an aqueous solution; distilled water; or any combination thereof and soaking or, equilibrating it in a physiologically compatible saline solution prior to use. Notwithstanding these procedures problems often arise by way of an inflammatory or immunological response in the surrounding tissue. It is well known, for example, that a certain portion of users of soft contact lenses are observed to have an inflammatory or other discomforting response. For such persons, the wearing of soft lenses results in an irritation and or inflamation of the eyes. Accordingly, it is a primary object of the present invention to reduce or eliminate the adverse response of these users to soft contact lenses.